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Serena Williams, Victoria Azarenka and Roger Federer also are on the schedule

MELBOURNE, Australia (AP) — Serena Williams frightened a few people, including herself. Defending champion Victoria Azarenka had a momentary lack of concentration. Two of the biggest names on the men's side at the Australian Open — Roger Federer and Andy Murray — had straight-sets wins.

Day Two at Melbourne Park on Tuesday brought another day of perfect weather but a few anxious moments for Williams, who fell awkwardly on her right ankle in her 6-0, 6-0 win over No. 110-ranked Edina Gallovits-Hall.

Williams had the ankle heavily taped by trainers and was able to continue and still dominate the Romanian player. Later, she said she hoped to continue playing — she'll have a scheduled day off Wednesday, returning Thursday to play her second-round match — and maintain her quest of winning her third Grand Slam tournament in a row and sixth Australian Open.

"I think I was really, really close to panicking because a very similar thing happened to me last year, almost on the same side, the same shot," Williams said. "I just had to really remain calm and think things through."

She left little doubt she'll be back to play her second-round match Thursday against Garbine Muguruza of Spain, who needed a 14-12 win in the deciding set to clinch her first-round match Tuesday against Magdalena Rybarikova of Slovakia.

"Oh, I'll be out there," Williams said of her second-round match. "I'm alive. My heart's beating. I'll be fine."

Azarenka trailed 3-0 in the second set of her match with Monica Niculescu before leveling the set at 4-4 and winning 6-1, 6-4.

"I started well but I struggled a little in the second set," Azarenka said.

Told that her biggest threat on her half of the draw had injured her ankle, Azarenka wondered, tongue-in-cheek, how serious Williams' ailment could be: "I heard she won love and love, so what kind of injury are we talking about?"

Murray, playing with more confidence since his U.S. Open win in the final over Novak Djokovic that ended a 76-year drought for British men in majors, beat Robin Haase of the Netherlands 6-3, 6-1, 6-3. The second-seeded Federer defeated Benoit Paire of France 6-2, 6-4, 6-1.

Murray needed just 1 hour, 37 minutes, and Federer 1:23 in their first-round matches. They'll need to conserve their energy for a potential semifinal against each other to determine a final against top-seeded and defending champion Djokovic, assuming all three men are still around on the final weekend.

Before a ball was hit Tuesday, players and officials were shocked to hear of the serious illness and pending resignation of ATP World Tour executive chairman and president Brad Drewett. The ATP said in a statement Tuesday that Drewett, a former player, has motor neurone disease, or Lou Gehrig's disease, but will continue in his role on an interim basis until a successor is found "in the near future."

Drewett has held the top ATP position since Jan. 1 last year. The 54-year-old Australian was a top 40 singles and top 20 doubles player before he retired as a player in 1990.

Federer, president of the ATP Player Council, said the news was difficult for the tour and its players.

"I saw him yesterday and he told me the news," Federer said. "Obviously very emotional ..."

Murray said it was "shocking news."

"He's definitely had an impact in the time he's been working there," Murray said. "It's a big shame."

It was Murray's first Grand Slam match as a major champion.

"It didn't feel much different to me," he said. "I was still nervous before I went on to play the match.

"The benefits of that is if I get myself deep into a Slam this year and you're playing against the top players — that's when you'll draw on that experience and use it in the right way."

It's been 12 months since Murray started working with eight-time major winner Ivan Lendl, and he attributes much of the success in his breakthrough 2012 to his partnership with his new coach.

It's relaxed "in front of the cameras," Murray joked. "Behind closed doors he works me very hard ... he tells you exactly how it is and that's exactly what I needed."

Local hope Bernard Tomic, who beat Djokovic at the Hopman Cup two weeks ago, defeated Leonardo Mayer of Argentina 6-3, 6-2, 6-3 in a night match. Tomic has been on a New Year's high after winning his first ATP tournament on Saturday at the Sydney International.

Williams sounded almost matter-of-fact about her ankle ailment and its potential to affect her play in the rest of a Grand Slam she has won five times.

"I've played this tournament with so many injuries and was able to come off pretty on top," she said. "So for me, it's just another page and a great story to tell the grandkids one day."

Williams is favored to win the season's first major, coming into Melbourne with 35 wins in her previous 36 matches, including titles at Wimbledon, the London Olympics and the U.S. Open.

In other women's matches, former No. 1-ranked Caroline Wozniacki won the last six games to beat Sabine Lisicki of Germany 2-6, 6-3, 6-3 to advance along with No. 16 Roberta Vinci, No. 17 Lucie Safarova and No. 29 Sloane Stephens, the American teenager who beat Simona Halep of Romania 6-1, 6-1.

It was way hot on Day 4, and this is how Andreas Seppi of Italy cooled off after defeating Denis Istomin of Uzbekistan 7-6 (7-4), 5-7, 6-7 (3-7), 7-6 (7-3), 6-2. Temperatures reached 106 degrees at Melbourne Park.
Fiona Hamilton, AP

After a singles win Serena Williams, left, returned to the court to win a doubles match with sister Venus. They defeated Camila Giorgi of Italy and Stefanie Voegele of Switzerland 6-3, 6-1.
Aaron Favila, AP

Bernard Tomic of Australia thrilled the home crowd with a come-from-behind 6-7 (4-7), 7-5, 7-6 (7-3), 7-6 (10-8) win against Daniel Brands of Germany. Next up for Tomic is Roger Federer.
William West, AFP/Getty Images

Sam Querrey talks with Brian Baker after Baker was forced to retire from their match because of a knee injury. Baker tore his lateral meniscus and has a locked knee. He'll need surgery and about four months to recover.
Chris Hyde, Getty Images

Former U.S. Open and French Open champion Svetlana Kuznetsova continued her comeback from a knee injury that kept her out of the U.S. Open, ending her run of 40 consecutive majors. Also, No. 14 Maria Kirilenko had a 6-4, 6-2 win over American Vania King, and China's Peng Shuai beat Canada's Rebecca Marino 6-3, 6-0.

And 42-year-old Kimiko Date-Krumm of Japan upset No. 12-seeded Nadia Petrova of Russia 6-2, 6-0 to become the oldest woman to win a singles match at the Australian Open.

While Serena Williams will have the day off to rest her weary ankle Wednesday — along with Murray and Federer — Djokovic returns to play his second-round match against American Ryan Harrison. Second-seeded Maria Sharapova takes on Misaki Doi of Japan and Venus Williams plays Alize Cornet, with a third-round matchup created if French Open champion Sharapova and Venus Williams win their matches.